#include<iostream>
#include<cstdio>
using namespace std;

int main()
{
  //因为Linux下一切皆文件，所以，向显示器打印，本质就是向文件写入，如何理解？
  //c 
  printf("Hello printf->stdout\n");
  fprintf(stdout,"Hello fprintf->stdout\n");
  fprintf(stderr,"Hello fprintf->stderr\n");

  //C++
  cout<<"Hello cout-> cout"<<endl;
  cerr<<"Hello cerr->cerr"<<endl;

  return 0;
}
